SAFETY, PHARMACOKINETICS, PHARMACODYNAMICS AND GONADOTROPIC SUPPRESSIVE EFFICACY OF COMBINATION NESTORONE AND TESTOSTERONE GEL IN MEN. PREPARATIONS ARE APPLIED TRANSDERMALLY Conduct a Phase Ib clinical trial to determine if the combination of drug formulation will efficiently suppress gonadotropin production. SAFETY, PHARMACOKINETICS, PHARMACODYNAMICS AND GONADOTROPIN SUPPRESSIVE EFFICACY OF COMBINED NESTORONE AND TESTOSTERONE GEL IN MEN? There are very few contraceptive options available to men. Studies indicate that men would use a safe and reversible method of contraception if one were available to them. One promising regimen involves a method of delivering androgen plus progestin in order to suppress sperm production. Previous studies demonstrated the gonadotropin and sperm suppressing capability of Nestorone gel and testosterone gel preparations applied transdermally. For the present study, both steroids have been combined into a single gel formulation. This Task Order is for the conduct of a Phase Ib clinical trial to test whether the combined Nestorone and Testosterone gel product maintains similar pharmacokinetic and pharmacodynamic properties as were found for the two steroids in separate gel formulations. If a combination Nestorone and T gel regimen is effective at gonadotropin suppression, the NICHD may elect to conduct a larger study to evaluate the product using contraceptive efficacy as the primary endpoint.